Composition of mixtures of vinyl and acrylate resins



Patented Feb. 16, 1943 UNITED STATES PATIENT OFFICE COMPOSITION OF MIXTURES OF VINYL AND AGRYLATE RESINS George M. Powell, Ill, Charleston, W. Va., assignor to Carbide and Carbon Chemicals Corporation, a corporation of New York No Drawing. Application February 11, 1939,

- Serial No. 255,985

SClaims. (01.260-32) This invention is concerned with improvements in vinyl resin coatings, and'it more particularly vinyl acetate, and containing about 87% vinyl chloride in the polymer. The application of these resins in coatings and lacquers is promoted by a variety of useful properties which these resins. possess, such as their strength and toughness, their chemical resistance and inertness, their high degree of resistance to water, as well as their lack of odor and inflammability. These excellent properties are detracted from to some extent by other qualities inherent in the resin, for example, incomplete resistance to light and heat, and the necessity of baking a vinyl resin finish at rather high temperatures to secure good adhesion to metals. In addition, films derived from vinyl resin lacquers containing certain pigments, notably white, such as titanium dioxide or white lead, showa definite tendency toward chalking on prolonged exterior exposure. Chalking is a defect whereby the coated surface becomes dull and lifeless because of a gradual superficial disintegration or weathering of the surface of the protective film under the action of intense solar radiation.

Likewise, the polymeric estersof the acrylic,

and methacrylic acids are known and have been suggested as bases for lacquers, and enamels.

z I part of vinyl resin and nine parts of acrylate or methacrylate resin to compositions comprising nine parts of vinyl resin and one part of acrylate or methacrylate resin. Within these limits, the resins are known to be compatible, that is, a clear film is deposited from solutions of the resins.

However, the aforesaid improvements are not all obtained when the resins are combined in all such proportions, but only inthose compositions wherein the acrylate or methacrylate resin constitutes at last about 10% of the total resin con- However, solutions of these resins of vis'cosities suitable for application to a surface by means of spraying, cannot be successfully sprayed because the resin has a distinct tendency to coagulate in' filaments or to cobweb, as this phenomenon is commonly referred to in the coating art. Moreover, these polymeric esters are characterized by a comparative weakness in film strength, In distinction to these undesirable properties, these resins are considered highly re sistant to. heat and light.

' ;[t has now been found that, by a proper combination of the aforesaid vinyl resins with the pclymeric "esters of the acrylic or methacrylic acids, the'above-i'nentioned defects of theseresins ca'iiiibe ameliorated. It hasbeen observed that these resins are compatible with each other at least in the range of compo itions comprising one tent but not substantially more than 25% of the total resin content. A preferred range is from 10% to about 15% of the total resin content.

Combinations of acrylate or methacrylate resins with vinyl resins coming within the above limits are characterized by ,freedom from objectionable "cobwebbing when their solutions are sprayed; by improved resistance to light and heat; and by good adhesion to metals. Furthermore, the film strength of the composition is su perior to that of the acrylate or methacrylate resin alone. Compositions greatly exceeding the upper limit of acrylate or methacrylate resin content indicated above, are characterized by excated by the limits above have superior resistance to heat and light but other objectionable characteristics of such compositions render them unsuitable for use as lacquer coatings.

The properties of the combination are at an optimum when a vinyl resin comprising a conjoint polymer of vinyl chloride with vinyl acetate containing 87% vinyl chloride in the polymer and having an average macromolecular weight of about 10,000 to 12,000 is combined with a commercial grade of polymethyl a-methacrylate (having an average macromolecular weight of about 17,000 to 20,000) in compositions in which the polymethyl a-methacrylate amounts to from about 10% to about 15% of the total resin content. The macromolecular weights were deter-x mined by Staudingers method from the viscosity of dilute solutions of the resin;

'11; has also been found that chalking of the finish can be substantially prevented ifv a pigment which normally induces chalking is first ground and dispersed in the acrylate or methacrylate resin before combining this resin with combinations containing the pigment dispersed initially in polymethyl methacrylate exhibit the best resistance to chalking of the combinations of vinyl resin with the various polymerized esters of acrylic or methacrylic acid.

The following examples will illustrate more clearly the practice 01' the invention:

The-vinyl resin used in.the following experiments was a conjoint polymer of vinyl chloride with vinyl acetate having about -87% vinyl chloride in the polymer and having an average macromolecular weight of about 11,500.

Example 1 The following compositions were prepared. Sample A.-Titanium dioxide pigment was milled into a commercial grade poiymethyl methacrylate polymer on a difierential speed roll mill. After the pigment was well dispersed, the homogeneous sheet was taken ofl the mill and dissolved in an appropriate solvent. resin was added in solution form to this pigment paste and the appropriate amount of plasticizer added.

Sample B.-Titanium dioxide pigment was milled into a part of the vinyl resin on a roll mill. The homogeneous sheet'was broken up and dissolved in appropriate solvents to form a pigment paste. Additional vinyl resin and some polymethyl methacryiate resin, both in granular form, were dissolved separately in appropriate solvents and these solutions were added to the pigment paste.

The ultimate composition of Samples A and B by weight was identical and was as follows:

Parts Polymethyl methacrylate resin 2.1

Vinyl resin 12.1

Titanium dioxide pigment -8.1 Di -(ethylene glycol monobutyl ether) phthalate 1.0

Blown castor oil 0.1,

Ketone and aromatic hydrocarbon thinner..- 75.7

Sample C'.This sample was prepared in the same manner as Sample B, with the exception that the ratio of vinyl resin to polymethyl methacrylate resin was 3 to 1. The ultimate composition of this sample was:

Parts Polymethyl methacrylate resin 3.5

Vinyl resin 10.5

Titanium dioxide pigment 8.1 Di -(ethylene glycol monobutyl ether) phthalate 1.0

Blown castor oil 0.1

Ketone and aromatic hydrocarbon thinner" 75.7

Sample D.-This sample was prepared in the same manner as Sample B, with the exception that no methyl methacrylate resin was used.

Ketone and aromatic hydrocarbon thinner" 75.7

Two coats of each of these lacquer finishes, binned to spraying viscosity, were applied by The vinyl spraying to steel panels over a baked vinyl resin primer coat. It is significant that none of these lacquers showed any objectionable tendency to string or cobweb" when sprayed, with the exception of Sample C. This sample contained the greatest amount of polymethyl methacrylate resin and displayed more tendency to cobweb" than the other samples, but it could still be' sprayed satisfactorily upon dilution. Sample C represents. about the maximum amount of this particular grade of polymethyl methacrylate which can be used in conjunction with the vinyl resins without encountering serious difliculty in spraying. However, if lower molecular weight.

vinyl resin or polymetlLvl methacrylate resin were used, this proportion may be increased somewhat.

The coated panels were baked for thirty minutes at 280-,F. They were then exposed to a the finish is, of course, immaterial. However,

in this latter case, it is still equally important to use only the proportions specified of the polymethyl methacrylate or other acryiateresin in the finish in order to secure the other desirable properties enumerated above.

Example 2 stantially identical to Samples A and B when subjected to South Florida exposure at 45 to horizontal. The rating below was visual and is on the basis of 10=no chalking, 8=slight chalking, 6=considerable chalking, 4=bad chalking, 2=very bad chalking.

Sample A pigment Sample B- ground in pigment 4 poiymethyl ground in methacrylvinyl resin ate resin 4 weeks 10 10 6 weeks l0 6 10 weeks. 10 4 14 weeks. 9 3 20 weeks 8 3 Improvement in the chalking resistance of the finish was noted when other acrylate resins were employed in a like manner, although the improvement was not so marked. Among the resins tested were included n-butyl methacrylate adherence to metals, its resistance to light and heat and by its ability to be. sprayed from solutions thereof without stringing, comprising a conjoint polymer of a vinyl halide with a vinyl ester of a lower aliphatic acid combined with a polymerized lower fatty alcohol ester of one of the group consisting of acrylic and methacrylic acids, said polymerized lower fatty alcohol ester being present in 'amounts from about 10% to about 25% by weight of the totalresin content of said coating composition. V

2. A coating composition characterized by its adherence to metals, its resistance to light and heat and by its ability to be sprayed from solutions thereof without stringing, comprising a conjoint polymer of vinyl chloride with vinyl acetate combined with polymerized methyl methacrylate resin, said polymerized methyl methacrylate resin being present in amounts from about 10% to about 25% by weight of the total resin content of the coating composition.

3. A lacquer sprayable without stringing comprising a solution in an organic solvent of a vinyl resin and a polymerized lower fatty alcohol ester of one of the group consisting of acrylic and methacrylic acids, said vinyl resin being a conjoint polymer of vinyl chloride with vinyl acetate, and said polymerized lower fatty 'alcohol ester being present in amounts from about 10% to about 25% by weight of the total resin content of the lacquer.

4. A lacquer comprising a solution in an organic solvent of polymerized methyl methacrylate resin and of a conjoint polymer of vinyl chloride with vinyl acetate, said polymerized methyl methacrylate resin being present in amounts from about 10% to about 25% by weight of the total resin content of the lacquer, and said lacquer being sprayable without stringmg- 5. Process for making a coating composition unusually resistant to chalking on application of a film thereof to an exposed surface, which comprises initially dispersing a while pigment into a polymerized lower fatty alcohol ester of one of the group consisting of acrylic and methacrylic acids, and thereafter combining the pigmented dispersion with a conjoint polymer of vinyl chloride with vinyl acetate, said polymerized lower fatty alcohol ester being present in amounts from about 10% to about 25% by weight of the total resin content of the coating composition.

6. Process for making a coating composition unusually resistant to chalking on application of a film thereof to an exposed surface, which comprises initially dispersing a white pigment in polymerized methyl methacrylate resin, and thereafter combining the pigment dispersion thus formed with a conjoint polymer of vinyl chloride with vinyl acetate, said methyl methacrylate resin being present in amounts from about 10% to about 25% by weight-of the total resin content of the coating composition.

'7. An article having a coating resistant to chalking on exposure thereof comprising, in combination, a conjoint polymer of vinyl chloride with vinyl acetate, a polymerized lower fatty alcohol ester of an organic acid of the group consisting of acrylic and methacrylic acids, and a white pigment; the chalking tendencies of said pigment having been substantially neutralized by its being initially ground into said polymerized lower fatty alcohol ester, and. said polymerized lower fatty alcohol ester being present in amounts from about 10% to about 25% by weight of the total resin content of the coating.

8. A coating composition unusually resistant to chalking on application of a film thereof to an exposed surface, comprising in combination a conjoint polymer of vinyl chloride with vinyl acetate, a polymerized methyl methacrylate resin, and a white pigment, the chalking tendencies of said pigment having been substantially neutralized by its being initially ground into said polymerized methyl methacrylate resin, and

said polymerized methyl. methacrylate resinof the coating composition.

GEORGE M. POWELL, III. 

